You are welcome! I wish you a lot of fun and a fine process!
Respectfully
~Richard

Hi Duke,

it was a blast, so I strongly encourage others to do it. This was one of my first turnings, so I'm sure you will be able to put my work to shame as it gets even easier/prettier with practice. I couldn't have done it though without the advice of the other posters on HB since I didn't know what I was doing at all when I started this project.

Hugh

I have been working on replacing the plastic handles and knobs on my brass Europiccola (late pre millenium).

I made the group handle from brass because brass is dense enough to prevent the handle from rising when a vacuum forms after it cools. I made the portafilter handle from solid ebony with no insert. I made the steam knob from ebony with a brass shaft and insert.

The next project is the steam knob. This is in the planning stage. I could cut up a stock la Pavoni boiler cap. I examined mine carefully with a stereo mciroscope, I had thought the threads were cut after moulding the piece, but the threads are moulded too. It is cheaply made, even though they charge outrageous prices for them. I want to make a fully better one, including replacing their cheap threaded parts. I think the design to attach it as described in other posts here seems most sensible. Anyone know what polymer is used to make the original cap? I do not think it phenolic. What I need is a good machinable polymer that has an high enough glass temperature. One possible one is the so called PEI? With the right polymer cutting threads in it should not be that much of a problem. (I hope!!!)

I do not like the idea of having the base of the cap made of brass because metal against metal really requires lubrication, and I do not want the lubricant in my espresso! Furthermore machinable brass (360) has very high lead content, and 120 degree steam will constantly be condensing on it, washing the Pb into the espresso. Also if I were to cross thread a brass base it could damage the threads on the top of the boiler.

Any suggestions?

I have no specifics as to the heat capacity of this material, but I do recall when I had a custom made billards cue made up about 10 years ago, the friend of mine who made it used several parts that he milled out of Delron. He couldn't say enough about how hard and durable it is. I think it is inert and food safe. I'm certain if you turned the threads yourself, they'd never wear out. I just don't know if it expands excessively with heat or would be prone to cracking.

http://www.professionalplastics.com/DELRINSHEET-ROD